Liquid Biopsies Improve Ovarian Cancer Recurrence Detection

Liquid biopsies can detect ovarian cancer recurrence long before the tumor reappears, a new study found.

The study, published in ScientificReports, included 10 patients with advanced stages of ovarian cancer who had their blood drawn before and after surgery. Researchers used mate-pair sequencing to compare DNA from the liquid blood biopsies to DNA tissue samples taken from the tumor.

“In this study, the blood drawn before and after surgery and the surgical tissue was used to identify DNA fragments with abnormal junctions that can only be seen in this patient’s tumor DNA,” said researcher George Vasmatzis, PhD. “Next generation mate-pair sequencing was used to identify specific DNA changes of the tumor to create an individualized monitoring panel for liquid biopsy. This allows us to shape treatment to the individual patient rather than using a standard treatment that may not work for everyone.”

The results of the study revealed that when post-surgery DNA matched the tumor, patients had recurrence of ovarian cancer later on. When the post-surgery DNA did not match the tumor DNA, patients were found to be in remission.

Assay Schema

(A) Blood is drawn before and after surgery. DNA from tumor is sequenced using the next-generation mate-pair sequencing (MPseq) protocol to identify chromosomal rearrangements. Several junctions are chosen to construct a personalized panel for each tumor. Percent of ctDNA out of total cfDNA is calculated at each time point of blood collection. (B) Number of junctions identified in cohort of 10 cases of serous stage 3 ovarian cancer. Count numbers are above the bars with the expected false negative count in parenthesis. cfDNA: cell-free DNA; ctDNA: circulating tumor DNA.

In 2015, more than 21,000 women in the United States were diagnosed with ovarian cancer, and 14,000 died from the disease, the study cited. Often, the tumor cannot be detected until the late stages of the disease, causing ovarian cancer to have one of the highest death rates of all gynecological cancers.

Although most patients go into remission after the initial treatment, the tumor ends up returning 75% of the time, and typically does not respond to chemotherapy.

“With liquid biopsies, we don’t have to wait for tumor growth to get a DNA sample,” Vasmatzis said. “This important discovery makes it possible for us (to) detect recurrence of the disease earlier than other diagnostic methods. We can repeat liquid biopsies to monitor the progression of the cancer. That gives hope of a better treatment plan over time.”

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Exosomes are cell-derived vesicles that are present in many and perhaps all biological fluids, including blood, urine, and cultured medium of cell cultures. Exosomes contain various molecular constituents of their cell of origin, including proteins and RNA. It is becoming increasingly clear that exosomes have specialized functions and play a key role in, for example, coagulation, intercellular signaling, and waste management. - from wikipedia